The sidebar is a different case, because opening a menu and expanding a tree
are very different things. Also, there should be a delay for the tree, but not
for the menu. I've split the sidebar case off to bug 101446.
I think it's implicit that dragging the proxy icon should act like dragging a
link, so I'm removing that from the summary.

Adding Dean Tessman since he fixed bug 30861 and might be interested in helping
here.
Personally, I think this bug is only marginally less important than bug 30861
(Pri=P3, TM=0.9.7) because once you've created a few (1-3) folders in the
personal toolbar, it becomes an (ever growing) primary location for frequently
used bookmarks ;)

Build 2002-04-03-03 WinMe
I made a new subfolder and tried to drop a proxy icon in it; the submenu with
Empty appeared but I couldn't drop the bookmark there. Then in Bookmark Manager
I moved the bookmark that got created above the subfolder into the subfolder.
Then I tried to drag another proxy icon into the subfolder and it did not open.
But menus right under "Personal Toolbar Folder" (i.e. represented as top-level
menus on the toolbar) do open fine for me. They do not close automatically,
however... (another bug)